In the prior art, a widely known neutralization device performs electrical neutralization by applying a voltage to a discharge electrode to produce a corona discharge, which generates ions, and ejecting the ions toward a neutralization subject. A discharge electrode used in such a neutralization device has the form of a truncated cone in which a distal portion of the discharge electrode gradually widens from a distal end toward a basal end. This increases the strength of the entire discharge electrode (e.g., refer to patent document 1).    Patent Document 1: Japanese Unexamined Utility Model Publication No. 5-17999